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UNITED STATES PATENT OFFICE.

JOHN A. JUST, OF NEW YORK, AND FRANK A. FLETCHER AND CALLIE F. GIBBS, OFNVATERTONVN, N. Y.; SAID JUST AND GIBBS ASSIGNORS TO SAID FLETCHER.

PROCESS OF BLEACHING MECHANICAL WOOD PULP AND OTHER RAW VEGETABLE FIBERSFOR THE PURPOSE OF MANUFACTURING PAPER. E

FBPECIPICATION forming part of Letters Patent No. 348,165, dated August24, 1886.

Application filed October 9, 1885. Serial No. 179,430. No specimens) Toall whom it may concern:

Be it known that we, JOHN A. JUST, a citizen of Germany, and a residentof the city, county, and State of New York, and FRANK 5 A. FLETCHER andCALLIE F. GIBBS, both citizens of the United States, and residents ofWVatertown, in the county of Jefferson and State of New York, haveinvented a new and Improved Process of Bleaching Mechanically- PreparedVood Pulp and other Raw Vegetable Fibers; and we do hereby declare thefollowing to be'a full and exact description thereof.

Our invention consists in an improved pror cess of bleaching wood fiberswhich have been reduced to pulp by mechanical means, and other rawvegetable fibers, for the purpose of manufacturing paper therefrom.Hitherto these fibers have not been extensively used for this purpose,both because of previous inability to bleach them and on account oftheir hardness and brittleness. By our improved process the fibers arequickly and economically bleached without materially injuring the mostdelicate fibers, and at the same time are rendered soft and pliable. Inthe processes hitherto tried, and in which heating or boiling has beenresorted to, chlorine, which is always contained in the bleaching agent,is left 3c insol'ution in the water in such quantities as to render theatmosphere very injurious to the health of the workmen and others whochance to inhale it, on account of the irrespirable character ofchlorine .gas. Substances 3 5 containing chlorine are also used in ourprocess; but since it is conducted without any heating or boiling allpossible escapeof chlo-' rine is prevented, and no injurious effectsresult from its practice.

The old and well-known process which has hitherto been used inendeavoring to bleach wood pulp consists in preparing oxygen andapplying the same, the oxygen being evolved by heating a metallic oxidein a clear solution of chloride of lime. This process, however,

fails to bleach raw vegetable fibers and mechanically-prepared woodpulp, although it does bleach all chemically-isolated fibers, such asunbleached chemically-prepared wood pulp, 5o rags, cotton, and wastes ofthe same.

It has long been known that chloride of lime or water saturated withchlorine not only refuses to bleach mechanically-separated wood orvegetable fibers, but, on the contrary, produces intense colors; andstrong acids turn mechanically-prepared wood pulp or raw vegetablefibers red in the sunlight, and often without sunlight in the presenceof moisture, and the slightest trace of iron contained in any of thematerials or vehicles employed in the bleaching, as in the water orlime, is sufficient to blacken the entire mass in a very short time.

The object of our invention is to bleach to a pure whitemechanically-prepared wood pulp and other raw vegetable fibers, and toobtain the same in a soft and pliable condition and without theapplication of heat. Ourimproved process achieves this result in apractical, feasible, economical, and efficient man- 7c ner.

In carrying out our process the usual beaterengine of the paper-mill ispreferably em 'ployed, and water is introduced into it in sufficientquantity to carry out the processsay enough to fill the engine abouthalf full. An emulsion is then introduced into the water in the engine,consisting of a mineral oil and a basic alkali or alkaline salt orsolution thereof. These latter principles are at the same timepreferably oxidizing agents, and may therefore be termed alkalineoxidizing agents. The mineral oilemployed is preferably petroleum orother oil obtained from the distillation of coal, and the alkalineoxidizing agent is preferably chloride of lime,or caustic lime andchlorine solution. Proper proportions of the ingredients of the emulsionare as follows: Four (4) pounds of petroleum and six (6) pounds ofchloride of lime to each one 0 hundred pounds, dry weight, of the woodpulp or other fiber. After the emulsion has been added to the water anddiluted thereby the wood pulp or other fiber is then introduced into theengine. The entire mass is then thor- 9 5 oughly agitated until theemulsion is brought into uniform and intimate contact with the fibersthroughout. The oily nature of the oil having disappeared in thepreparation of the emulsion, the emulsion acts as a favorable 10osolvent of the resinous and gummy materials which incrust the raw fibersin smallquantities, and as the operation advances it distinctly betraysits action on the fibers by as suming a slight but evident alcoholic andacetic odor. The wood pulp on becoming saturated by this solution losesits hardness and woody characteristics and becomes soft and pliableequally, as in the'case of chemicallyisolated fibers or rag-stock. Withthe aid of chlorine or any oxidizing or deoxidizin g agent present atthis stage of the process, the coloring-matter existing in the sapsubstances of the wood stuff is fully brought out, and is then bleachedpure white by the following treatment: The wood pulp under treatmentbeing now saturated with the emulsion dilute in water, three to four (3to 4) pounds of corn inon salt (sodium chloride) in solution are addedto each one hundred (100) pounds, dry weight, of the pulp or fiber. Thissolution being capable of dissolving a large quantity of chlorinegas,thus prevents any possible escape of the same,which otherwise wouldexpand and escape into the air, it being set free by the warmth which isevolved by the process of bleaching. Thus not only is no chlorine lost,but injurious effects to the workmen are avoided, since the chlorine isnot mechanically suspended in the mass, but is held dissolved in thedilute salt solution, and from that is abstracted as fast as required,to oxidize in the process of bleaching. To accelerate the process ofbleaching, a small quantity of acid, either vegetable or mineral-such asoxalic acid, for examp1emay be added, thus neutralizing alkalineprinciples favorable to oxidation. In bleaching some fiberssuch as flaxand jute, for example-the acid will be found necessary, but with thewood pulp is not absolutely essential, although preferable. Theproportion of acid which is properly used is three-quarters of a poundto each one hundred pounds of the fiber.

Instead of using an acid for the purpose of accelerating the process, asmall quantity of sulphate of zincsay two (2) to three (3) pounds toeach one hundred pounds of the pulpmay be advantageouslysubstituted asan equivalent thereof. The sulphate of zinc acts very energetically todecompose the chlorides, and thus liberate the chlorine, and if thewater originally introduced into the engine at the beginning of theprocess be warm (say from forty (40) to fifty ccntigrade) on thecompletion of the process the pulp is left in so nearly a neutral statethat little or no anti-chlorine is required, since there is at theconclusion little or no excess of chlorine.

The nextstage in the process consists in the introduction into the massof chloride of lime, chlorine gas, or water saturated with chlorine gas,together with a natron salt; or a potassium salt may be substituted forthe natron salt. The carbonate or sulphate of one of these bases is tobe preferred. The proper proportions of these ingredients to each onehundred pounds of pulp orfiber would be between thirty (30) and forty(40) pounds of the chloride, depending on its strength, and betweentwelve (12) and fifteen (15) pounds of the alkali carbonate or-sulphate.Upon the incorporation of these substances with the mass by agitation inthe beater'engine the wood pulp or other fiber is bleached permanentlyand perfectly white, owing to the decomposition of the hypochloritesformed with the above-mentioned bases. After the bleaching is completedany excess of chlorine is removed by an anti-chlorine substancesuch assodium hyposulphite or sulphurous-acid solution, for example-and theproduct is washed, and is then ready for being made into paper.

In case sulphate of zinc has been used to ac eelerate the process, therewill usually be no necessity for the use of anti-chlori ne, and hencethe washing may be dispensed with, since wash' ing is only essential topreveutbrownish tints being given to the pulp by the anti-chlorines.

In carrying out our invention, in practice we employ a beating-enginewhich will manipulate about five hundred pounds of the pulp or fiber.The steps of the process carried out with the preferred ingredients arethen as follows: First, the emulsion composed of petroleum and chlorideof lime is introduced; second, common saltis added; third, an acid orsulphate of zinc is introduced; fourth, chloride of lime and carbonateof soda are introduced. After the introduction of each ingredient theentire mass is thoroughly agitated, so as to subject every portion'ofthe mass to the action of the substances used.

We claim as our inveution-- 1. In the process of bleaching wood pulp andother fibers, treating the pulp or fiber,for the purpose of softeningthe same, with an emulsion composed of a mineral oil anda basic alkali,or alkaline salt or solution thercofisubstantially as set forth.

2. In the process of bleaching wood pulp and other fibers, treating thepulp or fiber,for the purpose of softening the same, with an emulsioncomposed of a mineral oil and an alkaline oxidizing agent, substantiallyas set forth.

3. In the process of bleaching wood pulp and other fibers in whichchlorine gas is evolved, introducing a solution of common salt,substantially as set forth, whereby the free chlorine is dissolved andits escape into the air prevented.

4. In the process of bleaching wood pulp and other fibers which have byprevious stages been reduced to a soft and pliable condition, treatingthe same with an oxidizing agent,together with an alkali basic salt,substantially as set forth.

5. The process of bleaching mechanicallyprepared wood pulp and other rawvegetable fibers,consisting of the following steps: First, treating thepulp or fibers with an emulsion composed of a mineral oil and analkaline oxidizing agent; second, addingasolution of coming product withan oxidizing or bleaching agent, together with a basic alkali salt, orsolution thereof, substantially as set forth. I 5

' In testimony whereof we affix our signatures in presence of twowitnesses.

JOHN A. JUST. FRANK A. FLETCHER. OALLIE F. GIBBS.

Witnesses:

GEO. H. WALKER, O. L. ADAMS.

